1. Field of the Disclosure
The present disclosure relates to a nano tube material and a method for manufacturing the same, and more particularly to a titanium oxide nano tube material in which crystal grains of the nano tube are oriented in a predetermined direction, and a method for manufacturing the same.
2. Description of the Related Art
One-dimensional nano tube architecture are advantageous in their unique charge transport and light penetration properties. Therefore, one-dimensional nano tube architecture have been under active research in the fields of solar energy conversion devices. In particular, nano tubes composed of titanium oxide and grown by anodizing have been conceived as one of the most promising photoelectrode materials in dye-sensitized solar cells (DSSC) due to efficient utilization of incident light and excellent charge collecting properties.
The titanium oxide nano tube-based DSSC is reported to have similar electron diffusion properties compared with nano particle film (NPF)-based DSSC. This is because the anatase crystals present in the photoelectrode of the DSSC have similar sizes and the crystal grains are oriented randomly. Therefore, if the TiO2 nano tube composed of a single crystal or multi crystals with good orientation is applied to DSSC, the electron transport property of the DSSC may be improved. In recent, Grimes group showed this possibility by using vertically aligned single crystalline rutile nanorods. Generally, the electron diffusion coefficient of rutile nanoparticles is lower than the anatase nanoparticles, but when the vertically aligned single crystalline rutile nanorods are applied to the DSSC system, it was found that similar electron diffusion characteristics with NPF may be obtained.
Usually, the electron diffusion coefficient of rutile nanoparticles is lower than the anatase nanoparticles. Although considerable efforts have been focused on the titanium oxide nano tube-based DSSC, the study on the fabrication of single crystal-like or preferred-oriented anatase TiO2 nano tube and the characterization of their charge transport properties has not been reported yet.
Typically, as-anodized amorphous nano tubes are transformed into the nano tubes composed of randomly oriented nano grains during an annealing process. This is responsible for the difficulty in the preparation of the single crystal-like or preferred-oriented anatase TiO2 nano tube.